replacing o2 sensors

I got a "check engine" light today, stayed on for about three seconds and turned off. I checked the codes and got a 32 and a 37 (both oxygen sensors). A few months ago my light came on one time, so that must have been for the other o2 sensor I guess. Anyway, should I just clear the codes and see if it comes up again, or replace them now? Is it something that needs replacing?

OK they are needed for the engine to run at the right mixture, it is what the computer makes its final adjustments with. If the are shot you will probibly notice a drop in fuel economy also. I would clear the computer then if they show again have them changed, I know they are not cheep but it is worth it.
I did the one in my NX not long back. $70 for a nice one but I think my fuel milage increased by 3 or 4 miles per gallon of gas.